U.S. patent application number 13/586389 was filed with the patent office on 2013-02-21 for original document size detection device.
This patent application is currently assigned to NEC ENGINEERING, LTD.. The applicant listed for this patent is Masaya IGAWA, Satoshi KOMATSU, Hiroyuki OKADA, Takao SAKURAI, Koushi TAKANO. Invention is credited to Masaya IGAWA, Satoshi KOMATSU, Hiroyuki OKADA, Takao SAKURAI, Koushi TAKANO.
Application Number | 20130044357 13/586389 |
Document ID | / |
Family ID | 47712467 |
Filed Date | 2013-02-21 |
United States Patent
Application |
20130044357 |
Kind Code |
A1 |
IGAWA; Masaya ; et
al. |
February 21, 2013 |
ORIGINAL DOCUMENT SIZE DETECTION DEVICE
Abstract
An original document size detection device characterized by
comprising a document reading table, a light source which
irradiates an original document placed on the document reading
table, a cover body which covers the original document, a light
detection unit which detects a reflected light that a light from
the light source is reflected by the original document, an angle
detection unit which detects an opening angle of the cover body and
has a first photo sensor, a second photo sensor, a third photo
sensor, and a shield plate, and a determination unit which
determines the size of the original document in a sub-scanning
direction when the opening angle of the cover body is equal to an
angle al and the size of the original document in a main scanning
direction when the opening angle of the cover body is equal to an
angle .alpha.2 (.alpha.1>.alpha.2) based on an output signal of
the light detection unit and an output signal of the angle
detection unit.
Inventors: |
IGAWA; Masaya; (Shizuoka,
JP) ; KOMATSU; Satoshi; (Tokyo, JP) ; OKADA;
Hiroyuki; (Tokyo, JP) ; TAKANO; Koushi;
(Tokyo, JP) ; SAKURAI; Takao; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IGAWA; Masaya
KOMATSU; Satoshi
OKADA; Hiroyuki
TAKANO; Koushi
SAKURAI; Takao |
Shizuoka
Tokyo
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
NEC ENGINEERING, LTD.
Tokyo
JP
NEC ACCESS TECHNICA, LTD.
Shizuoka
JP
|
Family ID: |
47712467 |
Appl. No.: |
13/586389 |
Filed: |
August 15, 2012 |
Current U.S.
Class: |
358/474 |
Current CPC
Class: |
H04N 2201/0081 20130101;
H04N 1/00708 20130101; H04N 1/00734 20130101; H04N 1/00835
20130101; H04N 1/00737 20130101; H04N 1/0071 20130101; H04N 1/00814
20130101; H04N 1/0075 20130101; H04N 1/1017 20130101; H04N 1/00713
20130101 |
Class at
Publication: |
358/474 |
International
Class: |
H04N 1/04 20060101
H04N001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 16, 2011 |
JP |
2011-178065 |
Claims
1. An original document size detection device characterized by
comprising a document reading table, a light source which
irradiates an original document placed on the document reading
table, a cover body which covers the original document, a light
detection unit which detects a reflected light that a light from
the light source is reflected by the original document, an angle
detection unit which detects an opening angle of the cover body and
has a first photo sensor, a second photo sensor, a third photo
sensor, and a shield plate, and a determination unit which
determines the size of the original document in a sub-scanning
direction when the opening angle of the cover body is equal to an
angle .alpha.1 and the size of the original document in a main
scanning direction when the opening angle of the cover body is
equal to an angle .alpha.2 (.alpha.1>.alpha.2) based on an
output signal of the light detection unit and an output signal of
the angle detection unit.
2. The original document size detection device according to claim 1
characterized in that the angle .alpha.1 is from 5 degrees to 25
degrees, the angle .alpha.2 is from 4 degrees to 24 degrees, and
the angle of (.alpha.1-.alpha.2) is equal to or greater than 1
degree and equal to or smaller than 10 degrees.
3. The original document size detection device according to claim 1
characterized in that the light source is turned on when a closing
angle of the cover body is equal to the angle .alpha.1, the
reflected light is detected by the light detection unit, and the
determination unit detects the size of the original document in the
main scanning direction based on the output signal of the light
detection unit.
4. The original document size detection device according to claim 1
characterized in that the shield plate has a first shield plate and
a second shield plate, the first shield plate and the second shield
plate have a notch and the light of the first photo sensor passes
through the notch of the first shield plate or is blocked by the
first shield plate according to the operation of the first shield
plate, and the light of the second photo sensor and/or the light of
the third photo sensor passes through the notch of the second
shield plate or is blocked by the second shield plate according to
the operation of the second shield plate.
5. The original document size detection device according to claim 1
characterized in that the first photo sensor and the second photo
sensor are disposed on different lines in a vertical direction,
respectively and the second photo sensor and the third photo sensor
are disposed at different positions on the same line in the
vertical direction, respectively.
6. The original document size detection device according to claim 1
characterized in that the original document size detection device
uses a hinge to open and close the cover body around a hinge
rotation shaft core which is disposed at one edge side of the
document reading table in the sub-scanning direction and the shield
plate is disposed at the end of the hinge rotation shaft core side
of the cover body.
7. The original document size detection device according to claim 1
characterized by comprising a masking unit which masks a signal
based on an incident external light when the opening angle of the
cover body is equal to the angle .alpha.2 that is included in the
output signal of the light detection unit.
8. An original document size detection device characterized by
comprising a document reading table, a light source which
irradiates an original document placed on the document reading
table, a cover body which covers the original document, light
detection means for detecting a reflected light that a light from
the light source is reflected by the original document, angle
detection means for detecting an opening angle of the cover body
and having a first photo sensor, a second photo sensor, a third
photo sensor, and a shield plate, and determination means for
determining the size of the original document in a sub-scanning
direction when the opening angle of the cover body is equal to an
angle .alpha.1 and the size of the original document in a main
scanning direction when the opening angle of the cover body is
equal to an angle .alpha.2 (.alpha.1>.alpha.2) based on an
output signal of the light detection means and an output signal of
the angle detection means.
Description
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2011-178065, filed on
Aug. 16, 2011, the disclosure of which is incorporated herein in
its entirety by reference.
TECHNICAL FIELD
[0002] The present invention relates to an original document size
detection device.
BACKGROUND ART
[0003] A device such as a copier, a facsimile machine, or the like
has an image reading unit. The image reading unit includes an
optical module. The optical module includes for example, a light
source, a photoelectric conversion element (for example, a CCD), a
plurality of mirrors, and a lens. The light source irradiates an
original document placed on a document reading table. The light
emitted by the light source is reflected by the original document
and the reflected light is reflected by the mirror to lead it to
the CCD. The lens is disposed between the mirror and the CCD,
concentrates the light reflected by the mirror, and forms an image
on the CCD. A wire is connected to the both ends of the optical
module. A drum around which the wire is wound is driven by rotation
of a motor. Whereby, the wire is spooled, the optical module is
pulled in a sub-scanning direction (the sub-scanning direction is
perpendicular to a main scanning direction), and the optical module
is moved parallel to the original document in the sub-scanning
direction. By this, the image is read. When a cover body of an ADF
unit (automatic document feeder) is closed after the original
document is placed on the document reading table, the image reading
unit detects (determines) the size of the original document in both
the main scanning direction and the sub-scanning direction (the
width and the length of the original document are detected).
Namely, the size such as A4 size, A3 size, B4 size, or the like of
the original document placed on the document reading table is
determined.
[0004] The size of the original document in the main scanning
direction (the length of the original document) is
detected/determined based on a change in an output waveform of the
CCD that appears at a certain position when the optical module
reads the original document in the main scanning direction. The
output waveform of the CCD greatly changes at a boundary between an
area in which the original document exists and an area in which it
does not exist when the original document is read in the main
scanning direction. Namely, because the output waveform of the CCD
greatly changes at the boundary, it can be known that the position
at which the output waveform of the CCD greatly changes is the
position of the edge of the original document.
[0005] A size sensor disposed to a rail in the sub-scanning
direction on which the optical module moves is used for the
detection of the size of the original document in the sub-scanning
direction. A photo sensor composed of a pair of units (a light
emission unit and a light reception unit) is used for the size
sensor. The original document is detected by the size sensor as
follows. The light emission unit of the size sensor emits the
light, the original document is irradiated with the light, the
light is reflected by the original document, and when the light
reception unit of the size sensor receives the reflected light, it
is determined that the original document exists. When the reflected
light from the original document is not received by the light
reception unit of the size sensor, it is determined that the
original document does not exist. The size sensor is composed of a
plurality of photo sensors (for example, two photo sensors). The
size of the original document in the sub-scanning direction is
determined based on the combination of the signals from two photo
sensors.
[0006] The basic technology method for detecting (determining) the
size of the original document placed on the document reading table
has been explained above. When the size of the original document in
the main scanning direction and the size of the original document
in the sub-scanning direction are detected, a specific opening
angle (closing angle) of the cover body of the ADF unit is used as
a trigger. For this reason, a cover body angle detection mechanism
is provided in a device in order to achieve the detection of the
size of the original document when the closing angle of the cover
body reaches a set angle (the specific closing angle).
[0007] The device disclosed in Japanese Patent Application
Laid-Open No. 2004-258386 (hereinafter, patent document 1) includes
two or three optical sensors that are disposed on one line in a
vertical direction and a sensor flag for blocking the light of the
optical sensor (the sensor flag moves upward and downward according
to a cover body opening angle). The opening angle of the cover body
is determined by the height position of the optical sensor that
detects the position (height) of the sensor flag.
[0008] The rotation angle detection device in which two sets of
combinations of angle data that are adjacent does not overlap
during one rotation of a rotation plate and a CPU calculates a
rotation angle of the rotation plate by comparing a combination of
a binary code obtained by the optical sensor and a past binary code
obtained at the previous time with the combination of the angle
data is disclosed in Japanese Patent Application Laid-Open No.
2006-177912 (hereinafter, patent document 2). As a result, the
rotation angle of the rotation plate can be obtained.
[0009] In Japanese Patent Application Laid-Open No. 2007-139607
(hereinafter, patent document 3), a sensor mounting structure
characterized in that a pair of transmission/reception vibrators is
held in a housing hole or by a housing holder in a point-contact
manner (or in a very light contact manner similar to the
point-contact manner) is disclosed. By this structure, the
vibration of the transmission/reception vibrator is less likely to
be transmitted to the housing hole or the housing holder and
whereby, a surface acoustic wave generated by one of the
transmission/reception vibrators is less likely to be transmitted
to the other transmission/reception vibrator (it is less likely to
act as disturbance).
[0010] However, in the device disclosed in patent document 1,
especially, when the cover body is closed at high speed, a problem
in which the size of the original document in a main scanning
direction cannot be correctly determined occurs. In a case in which
the size detection is performed twice for example, when the cover
body opening angle reaches 18 degrees and 12 degrees, a high-speed
response (a high-speed processing) cannot be achieved by using two
optical sensors. The problem generated when the cover body is
closed at high speed is caused by a time after the sensor is
physically switched until a control side recognizes the switching.
When the high-speed response is required, an interrupt processing
method by which the switching of the output signal of the sensor is
used as a trigger and the process starts when the trigger occurs is
used. In order to perform this interrupt processing, it is
necessary to set an interrupt detection port to the CPU at an
initial stage of designing a substrate. However, because the total
number of ports which can be set in the CPU is limited and the
number of ports required by the other function increases with the
increase of the number of functions provided for the device, the
interrupt detection port cannot be additionally provided.
Therefore, it is desirable that the number of the interrupt ports
used for the cover body angle detection is one. When two optical
sensors are used like the device disclosed in patent document 1,
the device cannot be realized by using one port. In patent document
1, a case in which three optical sensors are used is described.
However, in this case, the device using one port cannot be realized
like the case in which the device uses two optical sensors. For
this reason, when the necessity of increasing or decreasing the
number of the original document size detection angles occurs, this
cannot be achieved. Therefore, there is a possibility that the size
of the original document is erroneously detected when the cover
body is closed at high speed. In patent document 2 or 3, means to
solve the above-mentioned problem are not disclosed.
SUMMARY
[0011] An object of the present invention is to solve the
above-mentioned problem. In particular, the object of the present
invention is to provide a low price original document size
detection device which can correctly determine a size of an
original document placed on a document reading table even when the
cover body is closed at high speed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Exemplary features and advantages of the present invention
will become apparent from the following detailed description when
taken with the accompanying drawings in which:
[0013] FIG. 1 is a block diagram of an original document size
detection device,
[0014] FIG. 2 is a figure showing a relation between a photo sensor
and a cover body opening angle,
[0015] FIG. 3 is an explanatory drawing showing a method for
mounting an actuator unit that acts as a cover body angle detection
mechanism,
[0016] FIG. 4 is a side view showing a method for mounting a
transmissive photo sensor,
[0017] FIG. 5 is a front view showing a method for mounting a
transmissive photo sensor,
[0018] FIG. 6 is an explanatory drawing showing a relation between
a transmissive photo sensor and a shield plate when a cover body
opening angle .alpha.>18 degrees,
[0019] FIG. 7 is an explanatory drawing showing a relation between
a transmissive photo sensor and a shield plate when a cover body
opening angle .alpha.=18 degrees,
[0020] FIG. 8 is an explanatory drawing showing a relation between
a transmissive photo sensor and a shield plate when a cover body
opening angle .alpha.=12 degrees,
[0021] FIG. 9 is an explanatory drawing showing a relation between
a transmissive photo sensor and a shield plate when a cover body
opening angle .alpha.=0 degree,
[0022] FIG. 10 is a schematic perspective view of an original
document size detection device in a cover body open state,
[0023] FIG. 11 is a schematic perspective view showing an internal
mechanism of an original document size detection device,
[0024] FIG. 12 is a figure showing an internal mechanism of an
original document size detection device,
[0025] FIG. 13 is a figure showing a method for mounting a
reflection type size sensor,
[0026] FIG. 14 is an explanatory drawing showing an external light
entering a surface of a document reading table of an original
document size detection device when a cover body is closed,
[0027] FIG. 15 shows a CCD output when an external light enters a
surface of a document reading table of an original document size
detection device,
[0028] FIG. 16 shows a CCD output when an external light enters a
surface of a document reading table of an original document size
detection device, and
[0029] FIG. 17 shows a CCD output when an external light enters a
surface of a document reading table of an original document size
detection device.
EXEMPLARY EMBODIMENT
[0030] An original document size detection device according to the
present invention is installed in an image reading device such as
for example, a facsimile machine, a copier, a complex machine, or
the like. However, it is not limited to these devices.
[0031] The original document size detection device according to the
present invention has a function to automatically detect the sizes
of the original document in the main scanning direction and the
sub-scanning direction by an image reading device (for example, the
image reading device has the cover body which can be opened and
closed on the document reading table and reads an image of the
original document placed on the document reading table by moving
the CCD arranged in the main scanning direction of the original
document in the sub-scanning direction).
[0032] As shown in FIG. 1, the original document size detection
device comprises a document reading table 7, a light source 24
which irradiates an original document 13 placed on the document
reading table 7, a cover body (a document lid) 3 which covers the
original document placed on the document reading table 7, a light
detection unit (for example, a CCD) 25 which detects a light that
is emitted by the light source 24 and reflected by the original
document 13 placed on the document reading table 7, an angle
detection unit 33 which detects an opening angle of the cover body
and is composed of three photo sensors 32 (a first photo sensor
32a, a second photo sensor 32b, and a third photo sensor 32c) and a
shield plate, and a determination unit 5 which determines the size
of the original document 13 in a sub-scanning direction when the
opening angle (the closing angle) of the cover body 3 is equal to
the angle .alpha.1 and the size of the original document 13 in a
main scanning direction when the opening angle (the closing angle)
of the cover body 3 is equal to the angle .alpha.2
(.alpha.1>.alpha.2) based on an output signal of the light
detection unit 25 and the angle detection unit 33.
[0033] The original document size detection device of the present
invention will be described in detail below. At least when the
above-mentioned configuration is used, a low price document reading
device which can correctly determine the size of the original
document placed on the document reading table even when the cover
body is closed at high speed can be provided.
[0034] The determination units 5 is a computer and it is for
example, a CPU. Therefore, only one interrupt port is enough for
the detection of the cover body angle.
[0035] The angle (opening angle: closing angle) detection unit 33
(hereinafter called an actuator unit 33) for the cover body 3 is
composed of three transmissive photo sensors 32 (32a, 32b, and 32c)
and two shield plates 35 (a first shield plate 35a and a second
shield plate 35bc).
[0036] The actuator unit 33 further includes the base 37, a rod 34,
and a spring 36. The rod 34 is upwardly urged by the spring 36.
When the cover body 3 is in a closed state or in a closing state,
it is in contact with the end of the rod 34. Accordingly, the
position of the rod 34 in a vertical direction relates to the
closing angle (the opening angle) of the cover body 3. Namely, the
rod 34 moves up and down in conjunction with the opening/closing
operation of the cover body 3. Here, in a state in which the cover
body 3 is greatly opened by for example, 90 degrees (an angle
smaller than 90 degrees may be applied), even when a pressing
pressure from the cover body 3 side does not act on the upper end
of the rod 34 and an upward urging force is applied to the rod 34
by the spring 36, the rod 34 does not come off. In order to perform
this operation, for example, a structure in which a part of the
actuator unit 33 is latched at a proper position of the base 37 or
the chassis 38 and whereby, the rod 34 cannot move upward any more
is used. For example, a structure in which the shield plates 35
(35a and 35bc) cannot move upward from a position shown in FIG. 6
is used.
[0037] As shown in FIGS. 3 to 9, the transmissive photo sensors 32
(32a, 32b, and 32c) are disposed at a rear side of the device.
Because the transmissive photo sensors 32 are disposed at the rear
side of the device, it is not necessary to extend a cable to the
front side of the device, a short cable can be used, and whereby,
the cost of the device can be reduced. Three transmissive photo
sensors 32 (32a, 32b, and 32c) are arranged so that the photo
sensors are operated according to the operation table of FIG. 2A or
FIG. 2B.
[0038] The arrangement or the like of the photo sensors 32 will be
described in detail below. As shown in FIG. 4, a latching claw of
the transmissive photo sensor 32 is inserted in a hole provided to
a chassis 38. By this, the transmissive photo sensor 32 is latched
(fixed) to the chassis 38. If the transmissive photo sensor 32 is
used in this condition, there is a possibility that the latching
claw is unlatched by an external force because the transmissive
photo sensor 32 is only hooked in the hole by the latching claw. To
prevent this problem, a base 37 of an actuator unit 33 including
two shield plates 35 is pushed so as to make contact with the
transmissive photo sensor 32. Whereby, the actuator unit 33 is
inserted into a hole 49 of the chassis 38. Namely, the transmissive
photo sensor 32 is disposed so that it is sandwiched between the
base 37 and the chassis 38. After this, the actuator unit 33 is
fixed to the chassis 38 with a screw 50. By using this structure,
the transmissive photo sensor 32 is firmly fixed to the chassis 38
without looseness.
[0039] Three transmissive photo sensors 32 (the first photo sensor
32a, the second photo sensor 32b, and the third photo sensor 32c)
and two shield plates 35 (35a and 35bc) are configured as follows
(for example). The second photo sensor 32b and the third photo
sensor 32c are disposed at a side of the first photo sensor 32a.
The second photo sensor 32b and the third photo sensor 32c are
disposed on the same line in the vertical direction. The shield
plate 35a with the notch is disposed at a location corresponding to
the first photo sensor 32a. The shield plate 35a that moves upward
and downward blocks (intercepts) or transmits (receives) the light
of the first photo sensor 32a according to the position (the
height) of the shield plate 35a. The shield plate 35bc with the
notch is disposed at a location corresponding to the second photo
sensor 32b and the third photo sensor 32c. The shield plate 35bc
that moves upward and downward blocks (intercepts) or transmits
(receives) the light of the second photo sensor 32b and the light
of the third photo sensor 32c according to the position (the
height) of the shield plate 35bc. In particular, as shown in FIG.
6, the shield plate 35 and the transmissive photo sensor 32 are
disposed (arranged) so that the shield plates 35 (35a and 35bc)
does not block (intercept) the light of each of the transmissive
photo sensors 32 (the first photo sensor 32a, the second photo
sensor 32b, and the third photo sensor 32c) when the cover body 3
is sufficiently lifted.
[0040] When the cover body 3 is closed, the shield plate 35 and the
transmissive photo sensors 32 are disposed (arranged) so that the
positional relationship between them shown in FIG. 7 is obtained
when the cover body opening angle reaches the angle .alpha.1 (for
example, 18 degrees). Namely, the shield plate 35a is disposed
(arranged) so as to start to block (intercept) the light of the
first photo sensor 32a. Further, the shield plate 35bc is disposed
(arranged) so as not to block (intercept) the light of the second
photo sensor 32b and the light of the third photo sensor 32c.
[0041] When the cover body 3 is further closed, the shield plate 35
and the transmissive photo sensor 32 are disposed (arranged) so
that the positional relationship between them shown in FIG. 8 is
obtained when the cover body opening angle reaches the angle
.alpha.2 (for example, 12 degrees). Namely, because the light of
the first photo sensor 32a starts to pass through the notch of the
shield plate 35a, the state of the first photo sensor 32a changes
from a light shielding (blocking) state to the light receiving
state and the state of the second photo sensor 32b changes from the
light receiving state to the light shielding (blocking) state by
the shield plate 35bc. However, the third photo sensor 32c still
remains in the light receiving state. When the cover body 3 is
completely closed (the cover body opening angle is 0 degree), the
shield plate 35 and the transmissive photo sensor 32 are disposed
(arranged) so that the positional relationship between them shown
in FIG. 9 is obtained. Namely, because the light of the first photo
sensor 32a passes through the notch of the shield plate 35a, the
first photo sensor 32a still remains in the light receiving state
and the second photo sensor 32b still remains in the light blocking
(intercepting) state by the shield plate 35bc. However, the state
of the third photo sensor 32c that has been in the light receiving
state is changed to the light blocking (intercepting) state by the
shield plate 35bc.
[0042] As a result, the first transmissive photo sensor 32a, the
second transmissive photo sensor 32b, and the third transmissive
photo sensor 32c are set to a state (Low (light receiving state) or
High (light shielding state)) shown in the operation table of FIG.
2A (or FIG. 2B) by two shield plates 35 (35a and 35bc) that move
upward and downward together with the rod 34 that moves upward and
downward in conjunction with the closing angle (the opening angle)
of the cover body 3. In the above-mentioned specific example that
is composed of three photo sensors 32a, 32b, and 32c and two shield
plates 35a and 35bc, the angle .alpha.1 of 18 degrees and the angle
.alpha.2 of 12 degrees were used. The original document 13 is
placed on the document reading table 7 and the cover body 3 starts
to be closed. At the time of starting to close the cover body 3,
the positional relationship between three photo sensors 32a, 32b,
and 32c and two shield plates 35a and 35bc is shown in FIG. 6. At
this time, the shield plates 35a and 35bc does not reach the
position of each of the photo sensors 32a, 32b and 32c.
Accordingly, the light emitted by the light emission unit is
received by the light reception unit with respect to all the photo
sensors 32a, 32b and 32c. When the photo sensors 32a, 32b and 32c
are in this state, the output of each photo sensor is Low. The
output of each of the photo sensors 32a, 32b and 32c remains in a
Low state (the light reception unit receives the light emitted by
the light emission unit with respect to each of the photo sensors
32a, 32b, and 32c) until the opening angle (the closing angle) of
the cover body 3 reaches 18 degrees.
[0043] When the opening angle (the closing angle) of the cover body
3 reaches 18 degrees, the lower end of the shield plate 35a blocks
the light emitted by the light emission unit of the photo sensor
32a (refer to FIG. 7). By this, the output of the first photo
sensor 32a is changed (switched) from "Low" to "High". However, in
the second photo sensor 32b and the third photo sensor 32c, because
the shield plate 35bc does not block the light emitted by the light
emission unit of each of the photo sensors 32b and 32c, the light
emitted by the light emission unit of each of the photo sensors 32b
and 32c is received by the light reception unit of each of the
photo sensors 32b and 32c. Accordingly, the output of the photo
sensor 32b and the output of the photo sensor 32c are still "Low".
When the output of the second photo sensor 32b and the output of
the third photo sensor 32c are "Low" and the output of the first
photo sensor 32a changes from "Low" to "High", the opening angle
(the closing angle) of the cover body 3 is equal to the angle
.alpha.1 (for example, 18 degrees).
[0044] The cover body 3 is further closed. The output state of each
of three photo sensors 32a, 32b, and 32c is the same as the output
state when the opening angle (the closing angle) of the cover body
3 is equal to the angle .alpha.1 (for example, 18 degrees) until
the opening angle (the closing angle) of the cover body 3 reaches
the angle .alpha.2 (for example, 12 degrees).
[0045] When the opening angle (the closing angle) of the cover body
3 reaches the angle .alpha.2 (for example, 12 degrees), the
light-shielding by the shield plate 35a is released. Namely, in the
first photo sensor 32a, the light emitted by the light emission
unit is received by the light reception unit. Accordingly, the
output of the first photo sensor 32a is changed (switched) from
"High" to "Low". When the opening angle (the closing angle) of the
cover body 3 is equal to 12 degrees, the shield plate 35bc blocks
the light emitted by the light emission unit of the photo sensor
32b. By this, the output of the second photo sensor 32b is changed
(switched) from "Low" to "High". However, in the third photo sensor
32c, because the shield plate 35bc does not block the light emitted
by the light emission unit of the photo sensor 32c, the light is
received by the light reception unit of the photo sensor 32c (refer
to FIG. 8). Accordingly, the output of the photo sensor 32c is
still "Low". The cover body 3 is further closed. The output state
of each of three photo sensors 32a, 32b, and 32c is the same as the
output state when the opening angle (the closing angle) of the
cover body 3 is equal to 12 degrees before the cover body 3 is
completely closed. When the cover body 3 has been completely
closed, the output state of each of the first and second photo
sensors 32a and 32b is not changed but in the third photo sensor,
the light emitted by the light emission unit of the third photo
sensor is blocked by the shield plate 35bc (refer to FIG. 9).
Namely, the output of the third photo sensor is changed (switched)
from "Low" to "High".
[0046] Thus, two shield plates 35 (35a and 35bc) block (intercept)
and pass (transmit: receive) the sensor light of three transmissive
photo sensors 32 (32a, 32b, and 32c). The opening angle (the
closing angle) of the cover body is detected based on the
combination of the outputs of three transmissive photo sensors 32
(32a, 32b, and 32c). By using this mechanism, the size of the
original document can be detected by using the low price
transmissive photo sensor without using an expensive proximity
switch. Because the proximity switch provided at the front side of
the image reading device and a magnet attached to the cover body
are not required, a space can be reduced. By using the rod 34 with
the shield plate 35 shown in FIG. 3, the trigger for angle
detection is concentrated on only one photo sensor 32a and the
number of the interrupt detection ports can be reduced by one. As a
result, a signal is switched with respect to the cover body opening
angle at which the original document size detection is performed
and when the interrupt processing is performed, the cover body
opening angle is determined based on the operation table of FIGS.
2A and 2B. Therefore, the number of the cover body opening angles
that have to be detected can be increased or decreased and whereby,
the size of the original document can be surely detected.
[0047] When the size of the original document in the main scanning
direction 11 is detected, the light toward the original document
can not be completely blocked by the cover body 3. There is a case
in which the external light 28 such as the light of a fluorescent
lamp, the light of the sun, or the like may enter the CCD (light
detection unit) 25 in addition to the light that is emitted by the
light source 24 and reflected by the original document 13. The CCD
output waveform is affected by this external light 28. As a result,
the erroneous detection of the size of the original document
occurs. Therefore, the original document size detection device
according to the present invention includes a masking unit (not
shown) which masks the signal based on the incident external light
28 when the opening angle (closing angle) of the cover body 3 is
the angle .alpha.2 which is included in the output signal of the
CCD 25. The masking unit facilitates correct determination of an
original document end corresponding portion 29a with respect to
information (a CCD output waveform 29) obtained by performing a
photoelectric conversion of the light reflected by the original
document 13 that is read by the CCD 25. When the masking unit
performs an electric process to the CCD output information, a
desired area of the CCD output waveform 29 is masked. By using the
masking unit, even when the external light 28 enters, a region in
which the CCD output waveform varies by the external light 28 is
excluded when the CPU determines the size of the original document.
As a result, the size of the original document can be determined
without being affected by the external light.
[0048] For example, the image reading device such as a facsimile
machine, a copier, or the like usually uses a short focus lens
having a short optical path length from a viewpoint of weight
reduction, miniaturization, space saving, and cost reduction.
Because the short focus lens has a wide field angle, the view angle
of the optical module is wide. This means that the detection of the
size of the original document is affected by the external light
(for example, the light of a fluorescent lamp provided on a ceiling
or the light of the sun) 28 which cannot be blocked by the cover
body 3 when the cover body 3 is being closed. In other words, the
external light 28 which cannot be blocked by the cover body 3
enters the surface of the document reading table 7. When the size
of the original document in the main scanning direction 11 is
detected in this state, the waveform (the convex waveform) caused
by the external light 28 is generated in the CCD output waveform
when the original document 13 does not exist in an area which the
external light 28 enters. When the convex waveform is generated, it
is erroneously determined that the position of the convex waveform
end is the position of the edge of the original document 13.
Namely, the position of the edge of the original document cannot be
correctly detected.
[0049] Therefore, in the device using the short focus lens, in
order to solve this problem, extension of the cover body in a
direction toward a front side (a user side) of the device may be
performed. Namely, when the cover body 3 is extended in a direction
toward the front side (user side) of the device, the external light
28 does not enter the surface of the document reading table even
when the cover body 3 is being closed. Therefore, the erroneous
operation hardly occurs. However, when this method is used, the
size of the device becomes large. The masking unit performs the
electric masking process for masking the output waveform in an area
that corresponds to the area on the surface of the document reading
table which the external light 28 enters. By this, the size of the
original document can be correctly detected even when the cover
body 3 is not extended in the direction toward the front side of
the device (user side), and in other words, even when the external
light 28 enters the surface of the document reading table 7. By
this process, the convex waveform is electrically eliminated and
the detection of the size of the original document is not affected
by the external light 28.
[0050] The electric masking process is applied to the output signal
in an area that corresponds to an area between a position between
the edge of the original document having the maximum width in the
main scanning direction 11 and the edge of the original document
having a width that is one size smaller than the maximum width and
a maximum reading position in the main scanning direction. Namely,
the opening angle (the closing angle) of the cover body 3 when the
size of the original document in the main scanning direction is
detected is set so that the output signal in an area that
corresponds to the area on the surface of the document reading
table which the external light enters is masked by the electric
masking process. When the electric masking process is applied to
the output signal in the above-mentioned area and the output signal
does not remain in the High state in the masking area, it is
determined that the size of the original document in the main
scanning direction is a size corresponding to a position at which
the output signal changes from the High state to the Low state.
When the output signal remains in the High state in the masking
area, the edge of the original document cannot be discriminated.
Accordingly, in this case, it is determined that the size of the
original document is maximum. When the original document size
detection device is configured as described above, it is not
necessary to extend the cover body 3 in the direction toward the
front side of the device. Therefore, the size of the device can be
reduced. All sizes of the original documents can be detected
without being affected by the external light.
[0051] In the original document size detection device according to
the present invention, it is desirable that a hinge is used to open
and close the cover body 3 and a hinge shaft is disposed at one
edge side of the document reading table along the sub-scanning
direction. The shield plate 35 is disposed at the end of a hinge
rotation shaft core side of the cover body 3.
[0052] The original document size detection device according to the
present invention includes a movable optical module 22. As shown in
FIG. 12, the optical module 22 comprises the light source 24 which
irradiates the original document 13 placed on the document reading
table 7 of an image reading device 1, a plurality of mirrors 26
which reflects the light that is emitted by the light source 24 and
reflected by the original document 13 to lead it to a photoelectric
conversion element (CCD) 25, and a lens 23. The lens 23 is disposed
between the mirror 26 and the CCD 25, concentrates the light
reflected by the mirror 26, and forms an image on the CCD 25.
[0053] In order to move the optical module 22 in a sub-scanning
direction 10, as shown in FIG. 11, the optical module 22 is mounted
on an upper portion of two rails 43 that are disposed in the
sub-scanning direction 10. A wire 40 is connected to the both ends
of the optical module 22. In order to move the optical module 22 in
the sub-scanning direction 10, a drum 41 around which the wire 40
is wound and a drive unit 42 which rotates the drum 41 are
provided.
[0054] Two reflection type size sensors 44 are used for the
detection of the size of the original document in the sub-scanning
direction 10. As shown in FIG. 13, the reflection type size sensor
44 is composed of a pair of units (a light emission unit 45 and a
light reception unit 46). The reflection type size sensor 44 is
mounted on a rectangular substrate 47 whose long side is along the
sub-scanning 10 direction. The reflection type size sensor 44 is
held by two holders 48 fixed to the rail 43 on which the optical
module 22 is mounted. Further, the reflection type size sensor 44
is obliquely fixed.
[0055] The CCD waveform based on the light that is emitted by the
light source 24 and reflected by the original document 13 is used
for the detection of the size of the original document in a main
scanning direction 11 perpendicular to the sub-scanning direction
10. The opening angle (the closing angle) of the cover body 3 is
used as an activation trigger for turning on the light source 24
for the detection of the size of the original document.
[0056] In the original document size detection device according to
the present invention, the opening angle (the closing angle) of the
cover body 3 is set so that the output signal in the area that
corresponds to the area on the surface of the document reading
table which the external light 28 enters can be masked.
[0057] In a device disclosed in Japanese Patent Application
Laid-Open No. 2004-126132 (hereinafter, patent document 4), for the
purpose of accuracy improvement of the original document size
detection in the main scanning direction in which the
countermeasure against the external light is taken for the original
document size detection, when the cover body is closed, the size in
the main scanning direction is detected when the angle of the cover
body reaches a predetermined angle. The light source of the optical
module is turned off just before detecting the size of the original
document in the main scanning direction and the CCD output is read,
an incident position of the external light is detected, and this is
removed. By this, the influence of the external light is
removed.
[0058] However, in the device disclosed in patent document 4, the
CCD output is read twice, one is performed in a state in which the
light source is turned off and the other is performed in a state in
which the light source is turned on, in a short time until the
lifted cover body is closed. For this reason, when the cover body
is quickly closed by the operator, the original document detection
cannot follow the lid closing speed and whereby, a false detection
occurs. Usually, it takes several milliseconds to several tens of
milliseconds until the CCD or the light source for the optical
module stably operates after the power is turned on. Moreover,
because the number of times of reading the CCD output increases, a
software process becomes complicated.
[0059] In contrast, in the original document size detection device
according to the present invention, the angle of the cover body is
set so that the output signal in an area that corresponds to the
area on the surface of the document reading table which the
external light enters is masked by the electric masking process.
Accordingly, it is not necessary to confirm the CCD output in
advance in order to detect the incident position of the external
light 28. In a process for confirming the CCD output waveform for
original document size detection in the main scanning direction,
the masking process is performed by deleting only the output
waveform data in an area that corresponds to the external light
incident area. Therefore, a load on software control for deleting
the data in the area that corresponds to the external light
incident area does not become especially large. Of course, because
the data in the area that corresponds to the external light
incident area is excluded by the masking, the influence of the
external light can be removed. Accordingly, the influence of the
external light is removed by performing a few process and the
original document size detection determination can be performed
with high accuracy. A load on software control does not become
especially large because the electric masking process is used.
[0060] In the original document size detection device according to
the present invention, the cover body opening angle at which the
light source 24 is turned on and the cover body opening angle at
which the reading for size detection is performed can be
individually set.
[0061] In Japanese Patent Application Laid-Open No. 2006-261848
(hereinafter, patent document 5), as a method for detecting the
size of the original document, a method in which when it is
detected that the angle of the cover body reaches a specified
angle, the light source is turned on by using this as a trigger,
the detection operation is delayed for a predetermined time by a
software-controlled timer until an amount of light emitted by the
light source is equal to a specified amount of light, and when the
predetermined time has elapsed, the reading is performed is
proposed. However, even when this method is used, when the cover
body is quickly closed by the operator, there is a case in which
the reading for size detection starts after the cover body has been
completely closed because of mismatch between the predetermined
time of the timer and the lid closing speed. For this reason, there
is a possibility that the false detection occurs. Further, the
angle of the cover body at which the reading starts is not
specified. Therefore, the angle of the cover body at which the
reading starts is different for each operator because the cover
body closing speed is different for each operator by individual
variability. As a result, the result of the size detection varies.
In the device disclosed in patent document 5, only one angle can be
set with respect to the angle of the cover body that is used as the
trigger of the operation.
[0062] In contrast, in the original document size detection device
according to the present invention, a plurality of opening angles
of the cover body that are used as the trigger of the operation
(for turning on the light source and reading the original document)
can be set. Namely, the cover body opening angle at which the light
source is turned on and the cover body opening angle at which the
reading for size detection is performed can be individually set.
Therefore, the timing at which the light source 24 is turned on and
the timing at which the reading is performed can be controlled
separately. Because the operations are started at different
timings, in other words, the operations are started at different
cover body opening angles, the reading can be performed at the
predetermined timing without relation to operator's lid closing
speed. As a result, the accuracy of the original document size
detection is improved.
[0063] In the original document size detection device according to
the present invention, an angle range between 5 and 25 degrees is
desirable for the angle .alpha.1 and the angle range between 12 and
22 degrees is further desirable for the angle .alpha.1. The angle
range between 4 and 24 degrees is desirable for the angle .alpha.2
and the angle range between 8 and 18 degrees is further desirable
for the angle .alpha.2. Here, .alpha.1>.alpha.2. The angle range
between 1 and 10 degrees is desirable for the angle of
(.alpha.1-.alpha.2) and the angle range between 4 and 8 degrees is
further desirable for the angle of (.alpha.1-.alpha.2). The reason
that the above-mentioned range is desirable is described below.
When the angle .alpha.1 is too large, for example, the influence of
the external light becomes excessive and there is a high
possibility that the size of the original document is erroneously
detected. When the angle .alpha.2 is too small, a transition time
from the original document size detection operation to the next
operation is too short and whereby, there is a high possibility
that the size of the original document is erroneously detected. As
a result of various experiments, when the angle is within the
above-mentioned range, there was a small possibility that the size
of the original document is erroneously detected.
[0064] Next, the operation of the original document size detection
device according to the present invention will be described. The
detection of the size of the original document is performed by
using the opening angle (the closing angle) .alpha. of the cover
body 3 as a trigger. When the lifted cover body 3 is completely
closed (.alpha.=0 degree), the following operations (1) to (5) are
performed in order: (1) the cover body is lifted, (2) the light
source is turned on (.alpha.=18 degrees), (3) the size of the
original document in the sub-scanning direction is detected
(.alpha.=18 degrees), (4) the size of the original document in the
main scanning direction is detected (.alpha.=12 degrees), and (5)
the cover body is completely closed (.alpha.=0 degree). The angle
.alpha. is detected by the mechanism for detecting the angle of the
cover body 3 that is composed of three transmissive photo sensors
32a, 32b, and 32c and the actuator unit 33 (especially, two shield
plates 35a and 35bc) and the above-mentioned operations (1), (2),
(3), (4), and (5) are performed in order.
[0065] The above-mentioned operation (1) will be described in more
detail. When the cover body 3 is sufficiently lifted, the rod 34 of
the actuator unit 33 is not pressed by the cover body 3. At this
time, because three transmissive photo sensors 32a, 32b, and 32c
are in the "light receiving state", the cover body 3 is in a state
shown as "cover body opening angle>.alpha.1 (for example, 18
degrees)" in FIG. 2A. Therefore, the CPU determines that the cover
body 3 is lifted.
[0066] After this, when the cover body 3 is closed, by the shield
plates 35a and 35bc fixed to the rod 34 that moves in conjunction
with the cover body 3, three transmissive photo sensors 32a, 32b,
and 32c are set to a state indicated in the column "cover body
opening angle=.alpha.1 (for example, 18 degrees)" of the operation
table in FIG. 2A. The CPU receives the output information on three
transmissive photo sensors 32a, 32b, and 32c when the cover body
opening angle is equal to the angle .alpha.1 (for example, 18
degrees) and determines that the opening angle (the closing angle)
of the cover body 3 is equal to the angle .alpha.1 (for example, 18
degrees). The CPU uses this as the trigger and turns on the light
source 24.
[0067] The size of the original document in the sub-scanning
direction 10 is detected by using the turn-on of the light source
24 as the trigger. Namely, the size of the original document in the
sub-scanning direction 10 is detected based on the output signals
of two size sensors 44. A method for detecting the size of the
original document in the sub-scanning direction 10 is the same as
the conventional one. Therefore, the detailed explanation will be
omitted.
[0068] After this, the cover body 3 is further closed. Then, by the
shield plates 35a and 35bc fixed to the rod 34 that moves in
conjunction with the cover body 3, three transmissive photo sensors
32a, 32b, and 32c are set to a state indicated in the column "cover
body opening angle=.alpha.2 (for example, 12 degrees)" of the
operation table in FIG. 2A. The CPU receives the output information
on three transmissive photo sensors 32a, 32b, and 32c when the
cover body opening angle is equal to the angle .alpha.2 (for
example, 12 degrees) and determines that the opening angle (the
closing angle) of the cover body 3 is equal to the angle .alpha.2
(for example, 12 degrees). The CPU uses this as the trigger and
determines the state of the CCD output waveform 29 of the light
that is emitted by the light source 24 that is turned on when the
opening angle (the closing angle) of the cover body 3 is equal to
the angle .alpha.1 (for example, 18 degrees) and reflected by the
original document 13. When the opening angle (the closing angle) of
the cover body 3 is equal to the angle .alpha.2, the cover body 3
is not completely closed. Therefore, the external light 28 enters a
reading area on the surface of the document reading table.
Accordingly, the CCD 25 receives both the light reflected by the
original document 13 and the external light 28 and outputs the
combined information. As shown in FIG. 15, the combined information
(CCD output waveform) includes a convex waveform 30 caused by the
external light 28.
[0069] However, in the device according to the exemplary
embodiment, the masking unit performs the electric masking process
and the convex waveform 30 is masked as shown in FIG. 16. The CPU
determines that the output waveform end portion 29a in the "High"
state corresponds to the edge of the original document in the main
scanning direction 11. By this, the size of the original document
in the main scanning direction 11 can be known. However, as shown
in FIG. 17, there is a case in which the output waveform end
portion in the "High" state is included in the masking area. In
such case, the CPU determines that the size of the original
document in the main scanning direction 11 is maximum. Namely, by
performing the electric masking process, the influence of the
external light is prevented and the erroneous detection of the size
of the original document caused by the external light does not
occur.
[0070] After this, when the cover body 3 is further closed. Then,
by the shield plates 35a and 35bc fixed to the rod 34 that moves in
conjunction with the cover body 3, three transmissive photo sensors
32a, 32b, and 32c are set to a state indicated in the column "cover
body opening angle=0 degree" of the operation table in FIG. 2A. At
this time, the CPU determines that the cover body 3 is completely
closed.
[0071] In the original document size detection device according to
the present invention, two shield plates 35 (35a and 35bc) block
(intercept) and pass (transmit:receive) the sensor light of three
transmissive photo sensors 32 and the opening angles (the closing
angles) .alpha.1 and .alpha.2 of the cover body is detected based
on the combination of the outputs of three transmissive photo
sensors 32 (32a, 32b, and 32c). As a result, a low price original
document size detection device which can correctly determine the
size of the original document placed on the document reading table
even when the cover body is closed at high speed can be
provided.
[0072] The previous description of embodiments is provided to
enable a person skilled in the art to make and use the present
invention. Moreover, various modifications to these exemplary
embodiments will be readily apparent to those skilled in the art,
and the generic principles and specific examples defined herein may
be applied to other embodiments without the use of inventive
faculty. Therefore, the present invention is not intended to be
limited to the exemplary embodiments described herein but is to be
accorded the widest scope as defined by the limitations of the
claims and equivalents.
[0073] Further, it is noted that the inventor's intent is to retain
all equivalents of the claimed invention even if the claims are
amended during prosecution.
* * * * *